A prior art quick action coupling of this kind includes a coupling body and a coupling nipple, the coupling body comprising a coupling sleeve in which the coupling nipple is introducable to a sealing position. The wall of the coupling nipple is formed with radially extending through opening in which locking balls are radially movable between a locking position and a releasing position. In the locking position the balls project inside the inner surface of the wall of the coupling sleeve, and when the coupling nipple takes it sealing position in the coupling sleeve the locking balls engage a complementary recess in the coupling nipple so as to lock the nipple in the sealing position. In the releasing position the locking balls are positioned radially outside the locking position in which the balls engage the recess of the coupling nipple so as to allow that the coupling nipple is introduced into and withdrawn from the coupling sleeve. A locking sleeve is provided at the outer surface of the wall of the coupling sleeve and is axially displaceable between a locking position in which an inner locking surface of the locking sleeve engages the locking balls so as to retain the balls in the locking position, and a position in which the locking surface of the locking sleeve is at a distance from the locking balls so as to allow the balls to move radially outwards to the releasing position.
In this prior art quick action coupling it is necessary to manually displace the locking sleeve to the position in which the locking surface of the locking sleeve is at a distance from the locking balls, when the coupling nipple is introduced into the coupling sleeve as well as when the coupling nipple is withdrawn therefrom. Especially at the introduction of the coupling nipple into the coupling sleeve this is a substantial drawback as it is necessary concurrently to manipulate the coupling sleeve as well as to position the coupling nipple opposite to the opening of the coupling sleeve which is difficult to conduct by means of one hand and often requires that both hands are used.
In order to overcome this drawback and provide a quick action coupling in which the coupling nipple can be introduced into the coupling sleeve without manipulation of the locking sleeve it has been suggested to form the through openings of the coupling sleeve as slot-shaped openings. Thereby the slot-shaped openings extend in the longitudinal direction of the coupling sleeve and are of such extension in relation to the extension of the locking surface of the locking sleeve that the balls are adapted at the introduction of the coupling nipple into the coupling sleeve, while being affected by the nipple, and without axial displacement of the locking sleeve, to be displaced in the longitudinal direction of the slot-shaped openings away from an engagement with the locking surface of the locking sleeve, so as to allow the introduction of the nipple into the position in which the locking balls engage the recess of the nipple. The locking balls and also the locking sleeve are spring loaded towards the locking position.
In a quick action coupling of this kind the connection of the coupling body with the coupling nipple is simply conducted by forcing the coupling nipple into the coupling sleeve, the locking balls being thereby displaced in the slot-shaped openings to the position in which the balls are radially outside the locking position in which the balls engage the recess of the coupling nipple, while the locking balls move into the recess to take the locking position when the nipple has arrived to the position in which the recess of the nipple is opposite to the balls, and thereby the connection between the coupling nipple and the coupling sleeve has been completed.
A drawback of these prior art quick action couplings of this kind is that they are of a complicated construction for which reason they are costly and inclined to functional disorders.